And now, to the mystery of the coast guardman who vanished at sea more than three months ago. And then, he suddenly reappe at his home in hawaii. He's now in military custody while officials investigate what exactly happened. Abc's abbie boudreau has the latest on this bizarre case. Reporter: This morning, the u.S. Coast guard is trying to unravel just what happened to petty officer first class russell matthews, who has suddenly turned up after vanishing more than three months ago. They received a tip that petty officer matthews was at his wife's residence. Reporter: Police say when he mysteriously returned home sunday, he was incoherent. His neighbor heard him screaming for his family. We didn't know he was home until we heard him demanding he wants to see his wife and his children. Reporter: Matthews is a rescue swimmer, working for the coast guard in hawaii. In october, his car was discovered in this oahu woparking lot. At the time, friends cold police he was emotionally distraught. A massive search and rescue operation from the air and water turned up no clues. And after days after searching, the trail went cold. We covered 10,000 nautical miles. Within that search, it included an at-sea search and shoreside search. Reporter: At the time of his disappearance, the 36-year-old was being investigated for possible marijuana use, which could have led to his termination. Matthews' personal life suffered a blow, as well. He went missing one year after his wife was shot in the head. Although, it was ruled a suicide. He quickly remarried. Cares about his family. Reporter: This morning, matthews is considered a flight risk and is being held in military confinement until the coast guard can solve this mystery. For "good morning america," abbie boudreau, abc news, los angeles.

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